Cutter bits having reinforcing ribs



March 25, 1958 A. o. BRUESTLE ET AL 2,823,117

CUTTER BI'Ts HAVING REINFORCING RIBS -Filed Feb. s. 1955 ATTORNEYS.

' BY v 62 41/05 .49; ham-45K,

United States Patent" 2,828,117 CUTTER mrs HAVING REINFORCING urns Armin0. Bruestle and Claude B. Krekelen. Cincinnati,

Ohio, assignors to The Cincinnati Mine Machinery Company, incinnati,Ohio, a corporation of Ohio ApplicatiomFebruary 3, 1955, Serial No.485,888

3 Claims. (Ci- 262--33) In the artof making cutter bits for mining.machines it is well known to roll hardenable' steel to a rod of suitablecross" section, and then form individual bits by cutting the; rodintopieces. If the cuts are all parallel to each otherrhomboidal bitsare formed requiring one kind of bit holder. If successive cuts havedifferent angularities to the rod axis, trapezoidal bits'are produced,requiring The rod stoek'from which the bits are made may have differentcross sectional shapes. A generally diamond shape is usual. The termcutting point is not strictly accurate because the actual cutting endsof'thebits should not come to a pointlbut should have a certain breadthfor cutting efiic'iency'and stability. As a consequence the usualdiamond shape cross section of the bit rod stock has'comp'arativelywidely rounded corners at the ends of its major transverse axisto' givea desirable breadth at the cutting point. where rhomboidal bits aremade, the cutting points are to be found at'oppo's'ite sides of the rod;but they are found atthe same side of the rod when trapezoidal bits arebeing made.

, While bits of the types hereinabove described are relativelyinexpensive and are designed to be discarded when both points havebecome dulled or broken they have suiiered'fro'm the fact that theirservice life is comparatively shortfsof that the cost of their use isgreater than it should be. I

A primary objector this invention is to provide bits of the typesoutlined which have a very substantially lengthened service lifeattained at a negligibledncrease in cost.

' This and other objects of the invention which will be set forthhereinafter or will be apparent to one skilled in the art upon readingthese specifications, are accomplished by that construction andarrangement of parts and in those procedures of which certain exemplaryembodiments will now be described. Reference is made to the accompanyingdrawings wherein: 7

Figures 1 to Sinclusive are respectively of cross sections of rod stockswhich may be employed in the practice of the invention. 1 V

Figure. dis a partial elevational view of a bit having the im rovedcharacteristics. v i

'- Figure 7- tea partial, plan viewthereof;

Figure 8 is a partial end elevation thereof.

Figure 9 is a partial perspective view of another type of improved bitmade from the rod stock of Figure 4.

Figure 10 is a partial side elevation of a bit made from the rod stockof Figure 3.

Figure 11 is a partial plan view thereof.

Figure 12 is a side elevation of a rhomboidal bit.

Itwill be understood, of course, that Figure 13 is a side elevation'of atrapezoidal bit.

Figure 14 is a diagrammatic representation illustrative of theattainment ofia suitable clearance.

The invention here involved is based on the discovery that the strengthand wearing qualities of the cutting point of a bit are in large measuredependent upon the depth of metal lying immediatelybehindithe cuttingedge. The invention is therefore concerned primarily with increasingthis depth of metal without'significantly' adding to thecost ofmanufacture. As has been indicated, the conventional rod stock for bitmanufacture will have an edge or. opposed edges rounded orotherwiseconfigured so as to provide a cutting end of desired width whenthe rod stock. is cut transversely on a slantwise plane; but it Will' beevident that the actual cutting edge or point is relatively thin and hasvery little metal backing. As a consequence it is subject not only tocomparatively rapid wear but also to breakage or the spalling off of endportions. In essence, the present invention contemplates the provisionof a rib on the bar stock which extends beyond that edge portion orthose edge portions of the stock designed and configured to provide theactual desired cutting edge or point. The removal of an end portion ofthis rib in the final bit along a plane chosen to provide adequateclearance, results in the backing of the cutting edge or point by asubstantial depth of metal, therebyminimizing spalling and breakage andgreatly increasing the. wear resistance'. Bits produced in accordancewith this invention have a service life averaging several times thatofconventional bits formed by merely cutting the usual bar stock alongslantwise planes.

In Figure 1 there is illustrated thecross sectional shape of bar stockhaving a body 1 and side portions 2 and 3-' suitably configured for theformation of so called cutting points in the ways set forth above. Inaccordance with the teachings of this application the rod stock isformed with side ribs 4 and 5, somewhat narrower than the edge portions2 and 3 and projecting therebeyond as shown. The extra ribs 4 and 5 areindicated as rectangular in cross section, which is an advantageousshape. Lateral ribs 6' and 7 are shown in Figure 1 and are useful insome types ofbit holders for locating and stabilizing the bit. In Figure2 the lateral ribs have been omitted, the body 8 of the rod stock beingconventional in cross section excepting for the addition of the ribs 4and '5. 1

In Figure 3 there is shown a rod stock having a conventional crosssection as at 9 excepting for the addition. of edge ribs 10 and 11.These ribs are triangular in cross section and are somewhat more easilyrolled than the rectangular ribs 4 and 5.

Figure 4 is illustrative of arod stock 12 of somewhat different crosssection inasmuch as various external faces are concave as shown. In thisbit stock' the cutting points are designed to be formed at positionsindicated in dotted lines at A and B; and the added. ribs are. shown at13 and 14.

In Figure 5 a bar stock of diamond shape cross section is shown at 15.The cutting points are designed to fall at positions C and D; but theedge portionsof the mining machinery or the like, the bar stock fromwhich the bits are produced is so dimensioned that the actual cuttingpoints or edges (2, 3 in Figure 1; A, B in Figure be the cutting away ofthe extra rib adjacent the actual cutting end. Figure 6 illustratesthis. The bit having the body portion 1 and the cutting end portion 2has the extra rib 4 cut away along a plane 20. which lies .at a slightangle to the direction of cutting motion of. the bit in use asexemplified by the arrow E... This results not only in the provision ofa suitable clearance but in the backing of the actual cutting endportion 2 of thebit with a substantial thickness of metal extendingbackwardly of the direction of cutting. This is shown in both Figures 6and7. Figure 8 is a partial end elevation illustrative of the fact thatthe rib 4, cut away as shown, does not in any way interfere with thecutting action of the actual cutting end; but reinforces it against wearand breakage. The cutting'away of the rib 4 is most conveniently done bygrinding prior to the hardening of the bit although it maybe'accomplished in other ways.

The cross sectional shape shown in Figures 2 to inclusive may besimilarly treated. Figure 9 illustrates the manner in which the extrarib 13 of the cross sectional shape of Figure 4 is cut away along theplane 21, the cutting direction in this instancebeing shown by the arrowF. The bit shown in Figure 9 is a rhomboidal bit, so that at theopposite corner (not shown). the extra rib 14 will be similarly cutaway.

Figure is a partial side elevation of a bit made from the stock ofFigure 3, the extra rib 1% being cut away on the plane 22. Figure 11 isa partial top plan view of the same structure. Because of the triangularcross section of the extra rib 10 the cut plane 22 is also triangular inshape, but of very substantial depth. Figures 10 and 11 illustrate a bitwhich has been tipped with a hard alloy as at 23.

Figure 14 is a diagrammatic illustration showing a portion of a bithaving a body 24 and a cutting end 25 together with an extra rib 26. Therib adjacent the point is cut away along a plane 27, the line of travelof the cutting bit in use being illustrated by the line 28. Asillustrated, in order to obtain proper clearance, the angularity betweenthe plane 27 and the line of travel 28 should be definitely greater than0 but preferably less than about in order to secure maximumreinforcement. The dimensions of the extra rib 26 should preferably besuch as to give to the plane 27 a length in the line of travel of thebit of at least ,4, inch, but preferably inch or more as illustrated atG.

The bar stock for forming the improved bits of this invention can bemade for relatively little added cost of rolling; and since the extraribs are small in cross section the added Weight of metal is minor,costwise. The bar stock is ordinarily formed by rolling, although it maybe otherwise produced as by forging or machining. The cutting of the barstock is performed as usual, and there is no modification of the stepsof heat treating and hardening it current in the art. The steps ofgrinding away end portions of the extra rib or ribs, preferably donebefore the hardening step, is of minor cost. Thus the bits of theinvention are not significantly more costly than ordinary whileproviding a greatly enhanced service life. Where hard alloy tipping ispracticed, this may be done by procedures current in the art.

The bits moreover may for the most part be used interchangeably withconventional bits in the bit holders current in the art; and if such bitholders require modification at all this can readily be accomplished byrecessing them for the accommodation of the uncut away portions of theextra rib or ribs.

Modifications may be made in the invention without departing from thespirit of it. The invention having been described in certain exemplaryembodiments, what is claimed as new and desired to be secured by LettersPatent is:

1. A rolled steel rod stock for the formation of cutter bits, said stockbeing substantially diamond-shaped in cross-section with major and minortransverse axes, the said stock being of a width at points adjacent tobut spaced inwardly from the ends of its major transverse axis toprovide cutting ends, the said stock terminating at the ends of itsmajor transverse axis in reinforcing ribs of substantially rectangularcross-sectional configuration extending lengthwise of the stock, thesaid reinforcing ribs being of reduced cross-section with respect to thewidth of the stock at said cutting ends, but having a depth at leastsubstantially equal to the width of the cutting ends.

2. A rolled steel rod stock for the formation of cutter bits, said stockbeing substantially diamond-shaped in cross-section with major and minortransverse axes, the said stock being of a width at points adjacent to.but spaced inwardly from the ends of its major transverse axis toprovide cutting ends, the said stock terminating at the ends of itsmajor transverse axis in reinforcing ribs extending lengthwise of thestock, the said reinforcing ribs being of substantially less width thanthe said cutting ends whereby said ribs are demarked from said.

cutting ends by shoulders, said ribs having a depth at leastsubstantially equal to the width of the said cutting ends.

3. A cutter bit having a metallic body substantially diamond-shape ingeneral cross-section, said body being defined in side elevation byupper and lower parallel edge portions, and face planes meeting saidupper and lower edge portions respectively at acute and obtuse angles,said face planes having major and minor transverse axes and being of awidth at a point adjacent to but spaced inwardly from an end of themajor axis to provide a cutting end, the said face planes terminating atthe ends of their major transverse axes in reinforcing ribs extendingalong said edge portions, the said reinforcing ribs being of reducedcross-section with respect to the width of the said face planes at thesaid cutting ends, but having a depth at least substantially equal tothe width of the cutting ends, the said reduction in cross-sectionproviding shoulders at the juncture of said ribs and the remainder ofsaid body, the said ribs being cut away adjacent the said cutting endsat an angle to provide cutting clearance, whereby remaining portions ofsaid ribs adjacent said cutting ends serve to provide a backing for saidcutting ends.

4. The structure claimed in claim 3 in which the said ribs aresubstantially rectangular in cross-section.

5. The structure claimed in claim 3 wherein the said ribs aresubstantially triangular in cross-section.

6. The structure claimed in claim 3 wherein the said bit is generallytrapezoidal in side elevation.

7. The structure claimed in claim 3 wherein said bit is substantiallyrhomboidal in side elevation.

8. The structure claimed in claim 3 wherein the said bit has protrudingside ribs providing shoulders at the ends of the minor axes of said faceplanes.

References Cited in the file of this patent UNITED STATES PATENTS2,483,220 Morrow Sept. 27, 1949 2,483,221 Morrow Sept. 27, 19492,645,471 King July 14, 1953

